阅读说明：本技术 一种金属掺杂隐性锰钾矿分子筛催化剂及其制备方法和应用 (Metal-doped recessive manganese-potassium ore molecular sieve catalyst and preparation method and application thereof ) 是由 覃远航 罗海彬 杨犁 马广伟 王存文 汪铁林 吴再坤 张燎原 吕仁亮 马家玉 杜 于 2021-07-09 设计创作，主要内容包括：本发明提供了一种金属掺杂隐性锰钾矿分子筛催化剂及其制备方法和应用,制备方法包括如下步骤：S1、硫酸锰和硝酸钾溶于去离子水中,混合得到溶液A,将过硫酸氢钾和金属盐溶于去离子水中,混合得到溶液B；S2、将所述溶液A和溶液B混合,并置于高压反应釜内进行水热反应,将固体产物进行过滤、洗涤、干燥,研磨后即得到金属掺杂隐性锰钾矿分子筛催化剂。本发明利用水热合成法制备出粒径均一、核壳结构的金属掺杂隐性锰钾矿分子筛催化剂,该催化剂较常规的隐性锰钾矿型分子筛具有更高表面氧空穴密度,更大的比表面积和更优异的抗硫抗水性能,可有效提高烟气中NO的脱除率。(The invention provides a metal-doped recessive manganesium ore molecular sieve catalyst and a preparation method and application thereof, wherein the preparation method comprises the following steps: s1, dissolving manganese sulfate and potassium nitrate in deionized water, mixing to obtain a solution A, dissolving potassium hydrogen persulfate and metal salt in deionized water, and mixing to obtain a solution B; and S2, mixing the solution A and the solution B, placing the mixture in a high-pressure reaction kettle for hydrothermal reaction, filtering, washing and drying the solid product, and grinding the solid product to obtain the metal-doped recessive manganese-potassium ore molecular sieve catalyst. The invention utilizes a hydrothermal synthesis method to prepare the metal-doped recessive manganesium ore molecular sieve catalyst with uniform particle size and a core-shell structure, and the catalyst has higher surface oxygen hole density, larger specific surface area and more excellent sulfur-resistant and water-resistant performance compared with the conventional recessive manganesium ore molecular sieve, and can effectively improve the removal rate of NO in flue gas.)

1. A preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst is characterized by comprising the following steps:

s1, dissolving manganese sulfate and potassium nitrate in deionized water, mixing to obtain a solution A, dissolving potassium hydrogen persulfate and metal salt in deionized water, and mixing to obtain a solution B;

and S2, mixing the solution A and the solution B, placing the mixture in a high-pressure reaction kettle for hydrothermal reaction, filtering, washing and drying the solid product, and grinding the solid product to obtain the metal-doped recessive manganese-potassium ore molecular sieve catalyst.

2. The production method according to claim 1, wherein the mass ratio of the manganese sulfate, the potassium nitrate, the oxone, and the metal salt is (20:1) - (1: 1).

3. The method according to claim 1, wherein the metal doped in the metal salt comprises one or two of vanadium, aluminum, copper, cobalt, cerium and iron.

4. The method as claimed in any one of claims 1 to 3, wherein the hydrothermal reaction conditions include a reaction temperature of 100 ℃ and a reaction time of 1 to 24 hours at 250 ℃.

5. A metal-doped recessive manganesium ore molecular sieve catalyst, which is characterized by being prepared by the preparation method of the metal-doped recessive manganesium ore molecular sieve catalyst according to any one of claims 1 to 4.

6. The metal-doped recessive manganesite molecular sieve catalyst of claim 5, wherein the particle size of the metal-doped recessive manganesite molecular sieve catalyst is 2 μm to 4 μm.

7. The metal-doped recessive manganesium ore molecular sieve catalyst of claim 6, wherein the metal-doped recessive manganesium ore molecular sieve catalyst is fibrous or nested.

8. The application of the metal-doped recessive manganesium ore molecular sieve catalyst in selective catalytic reduction denitration according to any one of claims 5 to 7, which is characterized by comprising the following steps:

feeding flue gas to be treated into selective catalytic denitration equipment;

taking carbon monoxide in the flue gas as a reducing agent, and carrying out selective catalytic reduction reaction on the carbon monoxide and nitrogen oxides in the flue gas under the action of a metal-doped recessive manganese-potassium ore molecular sieve catalyst;

the nitrogen oxides are reduced into nitrogen, the carbon monoxide is oxidized into carbon dioxide, and the nitrogen and the carbon dioxide are output from an outlet of the denitration device.

9. The use according to claim 8, wherein the temperature of the selective catalytic reduction reaction is 150 ℃ to 300 ℃.

10. The use as claimed in claim 8, wherein the space velocity of the selective catalytic reduction reaction gas is 3000-^-1。

Technical Field

The invention relates to the technical field of flue gas catalytic denitration, and particularly relates to a metal-doped recessive manganese-potassium ore molecular sieve catalyst, and a preparation method and application thereof.

Background

The flue gas comprises flue gas discharged by power plants and metallurgical plants, wherein the flue gas generally contains nitrogen oxides (the content of the nitrogen oxides is 0.01-0.10%, and the nitrogen oxides comprise nitrogen monoxide and/or nitrogen dioxide, and the volume of the nitrogen monoxide in the nitrogen oxides is more than 90%), sulfur dioxide, water vapor, oxygen, carbon monoxide (the content of the nitrogen oxides is 0.08-1.0%), carbon dioxide and the like, and the pollution of the nitrogen oxides is serious, so that flue gas denitration is one of the problems which are urgently needed to be solved in the field of flue gas environment protection at present.

At present, the domestic and overseas flue gas denitration technology is mainly a Selective Catalytic Reduction (SCR) method. Commercially mainly used V₂O₅/TiO₂And V₂O₅-WO₃(MoO₃)/TiO₂The catalyst has the optimal activity temperature window of 300-400 ℃, and has good denitration activity and sulfur poisoning resistance. However, such catalystsThere are also some disadvantages: the active component vanadium has toxicity and is harmful to human health and environment; SO in flue gas₂Is easily oxidized into SO₃And NH with₃The ammonium sulfate salt generated by the reaction can cover the active sites of the catalyst and block the catalyst channels.

CO is used as a reducing agent, and the CO in the waste gas can be fully utilized to generate nontoxic CO2 and N2 after reduction, so that the content of CO in the discharged waste gas is reduced, the concentration of NOx is reduced, the waste is treated by waste, and the treatment cost is saved. However, in a catalytic reaction system using CO as a reducing agent, the catalyst has a large influence on the reaction, and the development of a novel catalyst with good denitration activity is significant.

Disclosure of Invention

In view of the above, the invention aims to overcome the defects of the prior art, and provides a metal-doped recessive manganese-potassium ore molecular sieve catalyst, and a preparation method and application thereof, so as to solve the problems of relatively high concentration of carbon monoxide and ammonia escape in flue gas in the prior denitration technology.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst comprises the following steps:

s1, dissolving manganese sulfate and potassium nitrate in deionized water, mixing to obtain a solution A, dissolving potassium hydrogen persulfate and metal salt in deionized water, and mixing to obtain a solution B;

and S2, mixing the solution A and the solution B, placing the mixture in a high-pressure reaction kettle for hydrothermal reaction, filtering, washing and drying the solid product, and grinding the solid product to obtain the metal-doped recessive manganese-potassium ore molecular sieve catalyst.

Optionally, in the above technical solution, a mass ratio of the manganese sulfate, the potassium nitrate, the potassium hydrogen persulfate, and the metal salt is (20:1) - (1: 1).

Optionally, in the above technical solution, the metal doped in the metal salt includes one or two of vanadium, aluminum, copper, cobalt, cerium and iron.

Optionally, in the above technical solution, the hydrothermal reaction conditions include a reaction temperature of 100 ℃ and 250 ℃ and a reaction time of 1-24 h.

The second purpose of the invention is to provide a metal-doped recessive manganesium ore molecular sieve catalyst, which is prepared by adopting the preparation method of the metal-doped recessive manganesium ore molecular sieve catalyst.

Optionally, in the above technical solution, the particle size of the metal-doped recessive manganesite molecular sieve catalyst is 2 μm to 4 μm.

Optionally, in the above technical solution, the metal-doped recessive manganesite molecular sieve catalyst is in a fiber shape or a nest shape.

The third purpose of the invention is to provide an application of the metal-doped recessive manganesium ore molecular sieve catalyst in selective catalytic reduction denitration, which comprises the following steps:

feeding flue gas to be treated into selective catalytic denitration equipment;

taking carbon monoxide in the flue gas as a reducing agent, and carrying out selective catalytic reduction reaction on the carbon monoxide and nitrogen oxides in the flue gas under the action of a metal-doped recessive manganese-potassium ore molecular sieve catalyst;

the nitrogen oxides are reduced into nitrogen, the carbon monoxide is oxidized into carbon dioxide, and the nitrogen and the carbon dioxide are output from an outlet of the denitration device.

Optionally, in the above technical solution, the temperature of the selective catalytic reduction reaction is 150-.

Optionally, in the above technical scheme, the space velocity of the selective catalytic reduction reaction gas is 3000-^-1。

Compared with the prior art, the metal-doped recessive manganese-potassium ore molecular sieve catalyst and the preparation method and application thereof provided by the invention have the following advantages:

(1) the invention utilizes a hydrothermal synthesis method to prepare the metal-doped recessive manganesium ore molecular sieve catalyst with uniform particle size and a core-shell structure, and the catalyst has higher surface oxygen hole density, larger specific surface area and more excellent sulfur-resistant and water-resistant performance compared with the conventional recessive manganesium ore molecular sieve, and can effectively improve the removal rate of NO in flue gas.

(2) The metal-doped recessive manganesium ore molecular sieve catalyst prepared by the invention has the reaction temperature of 150-^-1Under the condition of (3), the NO removal rate reaches 84-99.6%.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below to the drawings required for the description of the embodiments or the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic flow chart of a preparation method of a metal-doped recessive manganesite molecular sieve catalyst according to an embodiment of the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Referring to fig. 1, a preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst comprises the following steps:

s1, manganese sulfate MnSO₄·H₂O and potassium nitrate KNO₃Dissolving in deionized water, mixing to obtain a solution A, dissolving potassium hydrogen persulfate and metal salt in deionized water, and mixing to obtain a solution B;

and S2, mixing the solution A and the solution B, placing the mixture into a high-pressure reaction kettle for hydrothermal reaction, filtering, washing and drying the solid product, and grinding the solid product to obtain the metal-doped recessive manganese-potassium ore molecular sieve catalyst.

It can be understood that the cryptomelane type manganese oxide molecular sieve is a novel material similar to a zeolite type molecular sieve structure, has the advantages of large specific surface area, low isoelectric point, strong oxidation capacity and high cation exchange capacity, has rich pore structures, and shows excellent characteristics of electric conduction, magnetism, ion exchange, selective adsorption, catalysis and the like. According to the invention, the cryptomelane type manganese oxide molecular sieve is doped with metal elements, so that the catalyst with excellent catalytic activity is prepared on the premise of not changing the crystal form of the cryptomelane type manganese oxide molecular sieve.

Specifically, the mass ratio of the manganese sulfate, the potassium nitrate, the potassium hydrogen persulfate and the metal salt is 5:2:10: 1.

That is, the active component of the prepared metal-doped recessive manganesite molecular sieve catalyst comprises a cryptomelane type manganese oxide molecular sieve and a doped metal, and the molar ratio of manganese elements in the cryptomelane type manganese oxide molecular sieve to the doped metal elements is (20:1) - (1: 1).

Further, the metal doped in the metal salt includes one or two of vanadium, aluminum, copper, cobalt, cerium and iron.

In step S2, the hydrothermal reaction conditions include a reaction temperature of 100 ℃ and 250 ℃ and a reaction time of 1-24 h.

The raw materials used for preparation are low in cost, convenient and easy to implement. The metal-doped recessive manganesium ore molecular sieve catalyst is obtained through one-step hydrothermal synthesis, other active components do not need to be added into a load, the basic structure of the cryptomelane-based molecular sieve is kept unchanged by the catalyst, doped metal elements can enter a molecular sieve framework, and the preparation method is simple, low in raw material cost, convenient and easy to implement and suitable for popularization.

The second purpose of the invention is to provide a metal-doped recessive manganesium ore molecular sieve catalyst, which is prepared by adopting the preparation method of the metal-doped recessive manganesium ore molecular sieve catalyst.

The metal-doped recessive manganese-potassium ore molecular sieve catalyst is fibrous or nested and comprises single metal or double metal, and the particle size of the catalyst is 2-4 mu m.

The metal-doped recessive manganesium ore molecular sieve catalyst is of a core-shell structure and uniform in particle size, has higher surface oxygen hole density, larger specific surface area and more excellent sulfur-resistant and water-resistant performance compared with the conventional recessive manganesium ore molecular sieve, and can effectively improve the removal rate of NO in flue gas.

The third purpose of the invention is to provide an application of the metal-doped recessive manganesium ore molecular sieve catalyst in selective catalytic reduction denitration, which comprises the following steps:

1) feeding flue gas to be treated into selective catalytic denitration equipment;

2) taking carbon monoxide in the flue gas as a reducing agent, and carrying out selective catalytic reduction reaction on the carbon monoxide and nitrogen oxides in the flue gas under the action of a metal-doped recessive manganese-potassium ore molecular sieve catalyst;

3) the nitrogen oxides are reduced into nitrogen, the carbon monoxide is oxidized into carbon dioxide, and the nitrogen and the carbon dioxide are output from an outlet of the denitration device.

The temperature of the selective catalytic reduction reaction is 150-^-1。

It is understood that the exhaust gas generated from a coal-fired boiler, a petroleum catalytic cracking FCC unit, or the like, or a fuel engine, or the like, contains a large amount of CO.

The invention selectively catalyzes the reduction of NOx to N by using CO as a reducing agent₂And CO is oxidized to CO₂Simultaneously removing a part of CO in the denitration process; under the condition that the waste gas does not contain CO, the CO can be obtained by coal gasification and dry distillation, thereby reducing the storage space and the operation cost. Meanwhile, CO and SO cannot be generated in the operation process₂The fly ash is generated by the reaction, so that the pipeline is prevented from being blocked or the downstream equipment is prevented from being corroded. From the perspective of environmental protection, CO is a reducing agent with excellent performance, and CO can be used as the reducing agent to reduce NO, so that two harmful gases of CO and NO can be removed simultaneously, and the requirements of current environmental protection are met. The flue gas denitration scheme provided by the invention has a wide application range, and is particularly suitable for flue gas denitration of an ultra-low emission boiler.

On the basis of the above embodiment, the present invention provides the following specific examples of the preparation method and the application of the metal-doped recessive manganesium ore molecular sieve catalyst, and further illustrates the present invention. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are examples of experimental procedures not specified under specific conditions, generally according to the conditions recommended by the manufacturer. Unless otherwise indicated, percentages and parts are by mass.

Example 1

The embodiment provides a preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst, which comprises the following steps:

1) 0.69g of MnSO₄·H₂O and 0.83gKNO₃Dissolving the mixture in 25mL of deionized water, mixing the mixture with a solution of 7.5g of potassium hydrogen persulfate and 0.356g of cobalt nitrate in 50mL of deionized water, and violently and uniformly stirring the mixture;

2) transferring the mixed solution prepared in the step 1) into a 100mL reaction kettle with a polytetrafluoroethylene lining, carrying out sealed reaction at 120 ℃ for 24 hours, filtering, washing and drying the solid product prepared by the reaction, and then grinding the solid product into powder to obtain the recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.3.

The recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.3 prepared in example 1 is used, and the reaction temperature is 150 ℃, and the space velocity is 5000h^-1And the denitration reaction is carried out under the condition that the CO and the NO are respectively 1000 ppm.

And detecting the concentrations of NO and CO at the inlet and the outlet of the flue gas by using a flue gas analyzer, and calculating to obtain the catalytic denitration rate under the condition. The test results can be obtained, with a NO removal of 99.3% and a CO conversion of 88%.

Example 2

The embodiment provides a preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst, which comprises the following steps:

1) 0.69g of MnSO₄·H₂O and 0.83gKNO₃Dissolving the mixture in 25mL of deionized water, mixing the mixture with a solution of 7.5g of potassium hydrogen persulfate and 0.475g of cobalt nitrate dissolved in 50mL of deionized water, and violently and uniformly stirring the mixture;

2) transferring the mixed solution prepared in the step 1) into a 100mL reaction kettle with a polytetrafluoroethylene lining, carrying out sealed reaction at 120 ℃ for 24 hours, filtering, washing and drying the solid product prepared by the reaction, and then grinding the solid product into powder to obtain the recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.4.

The recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.4 prepared in example 2 is used, and the reaction temperature is 150 ℃, and the space velocity is 5000h^-1And the denitration reaction is carried out under the condition that the CO and the NO are respectively 1000 ppm.

And detecting the concentrations of NO and CO at the inlet and the outlet of the flue gas by using a flue gas analyzer, and calculating to obtain the catalytic denitration rate under the condition. The test results can be obtained, with a NO removal of 99.1% and a CO conversion of 89%.

Example 3

The embodiment provides a preparation method of a metal-doped recessive manganesium ore molecular sieve catalyst, which comprises the following steps:

1) 0.69g of MnSO₄·H₂O and 0.83gKNO₃Dissolving the mixture in 25mL of deionized water, mixing the mixture with a solution of 7.5g of potassium hydrogen persulfate and 0.593g of cobalt nitrate in 50mL of deionized water, and violently and uniformly stirring the mixture;

2) transferring the mixed solution prepared in the step 1) into a 100mL reaction kettle with a polytetrafluoroethylene lining, carrying out sealed reaction at 120 ℃ for 24 hours, filtering, washing and drying the solid product prepared by the reaction, and then grinding the solid product into powder to obtain the recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.5.

The recessive manganese potassium ore molecular sieve catalyst with the Co doping amount of 0.5 prepared in example 3 is utilized, and the reaction temperature is 150 ℃, and the space velocity is 5000h^-1And the denitration reaction is carried out under the condition that the CO and the NO are respectively 1000 ppm.

And detecting the concentrations of NO and CO at the inlet and the outlet of the flue gas by using a flue gas analyzer, and calculating to obtain the catalytic denitration rate under the condition. The test results can obtain that the NO removal rate is 98.9 percent and the CO conversion rate is 87 percent.

The combination of the above detection results shows that: the recessive manganese sylvite (OMS-2) molecular sieve has rich pore structure and mixed valence Mnⁿ⁺(n ═ 2, 3 and 4), and also strong ion exchange capacity, abundant lattice oxygen and acidic sites, exhibited excellent denitration performance.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.